Re: [PATCH v4 3/7] iommu/mediatek: Set MISC_CTRL register

From: Matthias Brugger
Date: Wed Jun 17 2020 - 05:35:02 EST




On 17/06/2020 05:00, Chao Hao wrote:
> Add F_MMU_IN_ORDER_WR_EN definition in MISC_CTRL.
> In order to improve performance, we always disable STANDARD_AXI_MODE
> and IN_ORDER_WR_EN in MISC_CTRL.
>
> Change since v3:

The changelog should go below the '---' as we don't want this in the git history
once the patch get's accepted.

> 1. Rename Disable STANDARD_AXI_MODE in MISC_CTRL to Set MISC_CTRL register
> 2. Add F_MMU_IN_DRDER_WR_EN definition in MISC_CTRL
> We need to disable in_order_write to improve performance
>
> Cc: Yong Wu <yong.wu@xxxxxxxxxxxx>
> Signed-off-by: Chao Hao <chao.hao@xxxxxxxxxxxx>
> ---
> drivers/iommu/mtk_iommu.c | 11 +++++++++++
> drivers/iommu/mtk_iommu.h | 1 +
> 2 files changed, 12 insertions(+)
>
> diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
> index 88d3df5b91c2..239d2cdbbc9f 100644
> --- a/drivers/iommu/mtk_iommu.c
> +++ b/drivers/iommu/mtk_iommu.c
> @@ -42,6 +42,9 @@
> #define F_INVLD_EN1 BIT(1)
>
> #define REG_MMU_MISC_CTRL 0x048
> +#define F_MMU_IN_ORDER_WR_EN (BIT(1) | BIT(17))
> +#define F_MMU_STANDARD_AXI_MODE_BIT (BIT(3) | BIT(19))
> +
> #define REG_MMU_DCM_DIS 0x050
>
> #define REG_MMU_CTRL_REG 0x110
> @@ -578,6 +581,14 @@ static int mtk_iommu_hw_init(const struct mtk_iommu_data *data)
> writel_relaxed(0, data->base + REG_MMU_MISC_CTRL);
> }
>
> + if (data->plat_data->has_misc_ctrl) {

That's confusing. We renamed the register to misc_ctrl, but it's present in all
SoCs. We should find a better name for this flag to describe what the hardware
supports.

Regards,
Matthias

> + /* For mm_iommu, it can improve performance by the setting */
> + regval = readl_relaxed(data->base + REG_MMU_MISC_CTRL);
> + regval &= ~F_MMU_STANDARD_AXI_MODE_BIT;
> + regval &= ~F_MMU_IN_ORDER_WR_EN;
> + writel_relaxed(regval, data->base + REG_MMU_MISC_CTRL);
> + }
> +
> if (devm_request_irq(data->dev, data->irq, mtk_iommu_isr, 0,
> dev_name(data->dev), (void *)data)) {
> writel_relaxed(0, data->base + REG_MMU_PT_BASE_ADDR);
> diff --git a/drivers/iommu/mtk_iommu.h b/drivers/iommu/mtk_iommu.h
> index 1b6ea839b92c..d711ac630037 100644
> --- a/drivers/iommu/mtk_iommu.h
> +++ b/drivers/iommu/mtk_iommu.h
> @@ -40,6 +40,7 @@ struct mtk_iommu_plat_data {
>
> /* HW will use the EMI clock if there isn't the "bclk". */
> bool has_bclk;
> + bool has_misc_ctrl;
> bool has_vld_pa_rng;
> bool reset_axi;
> unsigned char larbid_remap[MTK_LARB_NR_MAX];
>